全文获取类型
收费全文 | 916篇 |
免费 | 24篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 156篇 |
金属工艺 | 5篇 |
机械仪表 | 16篇 |
建筑科学 | 43篇 |
矿业工程 | 4篇 |
能源动力 | 19篇 |
轻工业 | 61篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 79篇 |
一般工业技术 | 150篇 |
冶金工业 | 267篇 |
原子能技术 | 8篇 |
自动化技术 | 106篇 |
出版年
2021年 | 20篇 |
2020年 | 14篇 |
2019年 | 11篇 |
2018年 | 22篇 |
2017年 | 11篇 |
2016年 | 13篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 51篇 |
2012年 | 28篇 |
2011年 | 54篇 |
2010年 | 18篇 |
2009年 | 28篇 |
2008年 | 31篇 |
2007年 | 31篇 |
2006年 | 33篇 |
2005年 | 22篇 |
2004年 | 27篇 |
2003年 | 22篇 |
2001年 | 6篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 53篇 |
1997年 | 33篇 |
1996年 | 15篇 |
1995年 | 23篇 |
1994年 | 17篇 |
1993年 | 15篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 23篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 15篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 14篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1972年 | 5篇 |
1965年 | 5篇 |
排序方式: 共有940条查询结果,搜索用时 234 毫秒
1.
2.
We demonstrate that alkali-halide salts, particularly potassium bromide, can reduce the photothermal emission (PTE) from single walled carbon nanotubes (SWNT). PTE is a prominent spectral feature in Raman spectroscopy when a near infrared laser is used to analyze a dark colored sample. We subsequently show that trapping salts inside SWNT and coating SWNT with the salt has a more pronounced impact on not only reducing PTE, but also enhancing the intensity of the Raman spectral features. The effect, which we have called nanotube enhanced Raman spectroscopy (NERS), has differences and similarities to the widely studied surface enhanced Raman spectroscopy (SERS). 相似文献
3.
A human fibroblastic cell line transformed by the SV40-T antigen sequence and continuously cultured for 7 months displayed large periodic variations in cell proliferation. This contrasted with other characteristics of this cell line that remained constant: mosaic cell shape, absence of cell contact inhibition, and predominance of a hypodiploid population. Similar fluctuations in proliferative capacity were also found during the long-term growth of a transformed but nonimmortalized human fibroblastic line prior to senescence, and in the established hamster fibroblastic Nil cell line. This growth pattern suggests a recurrent stimulation of growth in these three transformed cell lines. The proliferation pattern from cultured transformed cells may thus be complex and requires further investigation. These variations presumably influence major cell functions. This observation has important implications for the analysis of data from such cell lines. 相似文献
4.
5.
ED Schneiderman SM Willis CJ Kowalski TR Ten have 《Canadian Metallurgical Quarterly》1993,32(1):35-43
Sixty-five patients initially seropositive for IgM anti-phenolic glycolipid-I (PGL-I) antibodies were tested for antibody levels to PGL-I, lipoarabinomannan (LAM), and the 35-kDa protein of Mycobacterium leprae at regular intervals for up to 30 months following the commencement of multidrug therapy (MDT). There was a steady decline in IgM anti-PGL-I and anti-35-kDa antibody levels to a mean of 17% and 14%, respectively, of the starting level at 24 months. The development of type 1 and type 2 reactions or the presence of drug-resistant organisms in a small number of patients had no significant influence on the changes in antibody level. The rate of decline was similar in different disease categories, but a higher proportion of lepromatous patients remained seropositive at the end of 2 years of treatment than borderline tuberculoid patients. By contrast, the mean IgG anti-LAM antibody levels remained stable or increased. Again the occurrence of type 1 or type 2 reactions had no significant effect on antibody level over 2 years. Falls in the IgM anti-PGL-I antibody levels mirrored the falls in the bacterial index in individual patients and provide an additional parameter for monitoring the response to chemotherapy. 相似文献
6.
The emulsifying effect of a polyethylene-based ionomer on the phase size/composition relationship was studied for polypropylene/polyamide
and polyethylene/polyamide blends. The particle size measured for the uncompatibilized blends increased with minor phase concentration,
particularly as the region of dual phase continuity was approached. This relationship was less pronounced when ionomer was
added, and the dimensions of the dispersed phase were significantly reduced. A narrowing of the region of dual phase continuity
was observed due to the addition of ionomer. An increase in the torque measured during melt blending in a Brabender mixing
chamber resulted when ionomer was added, due to the increase in the interactions at the interface. The particle size determined
for the uncompatibilized blends increased with viscosity ratio. The effect was also less pronounced for the compatibilized
blends. From these observations, it was possible to conclude that the effect of interfacial modification on morphology predominates
over that of composition and viscosity ratio. The effects were interpreted in terms of the reduction of interfacial mobility
due to the compatibilization. 相似文献
7.
8.
The effectiveness of overlearning in enhancing performance has been acknowledged by researchers within the training community for years. In spite of this general consensus, the empirical basis for this claim is often not clear. This article presents a meta-analysis of the effects of overlearning on retention. Results indicate that overlearning produces a significant effect on retention of moderate overall magnitude and that the effect of overlearning on retention is moderated by the degree of overlearning, type of task, and length of retention period. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
James Rodgers Kaye Wolf Norm Willis Don Hamilton Ralph Ledbetter Curtis Stewart 《Color research and application》1994,19(5):322-331
A multiplant Quality Improvement Team [QIT] was firmed to develop and implement an evaluation program for various color measurement .systems as potential replacements for the then-current aging systems. The emphasis qf this article is the analytical methodology utilized to evaluate the various color systems. The evaluation program consisted cf two phases. Phase I was a general overview/review of several systems, while Phase II was an extensive internal comparative evaluation measurement systems. These were Milton-Roy's ColorMate HDS, HunterLab's Ultrascan, Datacolor's CS-5, and BYK-Gardner's The Color Sphere [TCS]. The main comparison criteria were interinstrument agreement [agreement between two instruments ofthe same system], user-friendly software and computer interface capability, vendor amenability to a long-term logistical and maintenance relationship, and price. All systems were evaluated by duplicate measurements on various color tiles, yarns, and polymer flakes-over 1600 measurements on each system. The systems were compared with an instrument matrix, a decision matrix, and a product matrix. The instrument matrix was a comparison qfinstrument parameters, software/math treatments, and economics. The decision matrix was a forced ranking of each system by each criteria category [1–4 scale, with 1 representing the best and 4 representing the worst]. The product matrix accentuated the relative importance ofone criterion category over another by multiplying the forced ranking by the criticality of the category. The criticality of a given category wus determined by consensus within the QIT. Thr combination qf the three matrices allowed the evaluator[.s] t o select the color rneasuremmt system that best satixfied the color measurement needs and requirements of their facility and their products. For this evaluation, all ofthe evaluated systems were superior to the then-current agingsystems. As a result of this methodology, one instrument emerged as clearly superior. © 1994 John Wrley & Sons, Inc. 相似文献
10.
Lu Shen Beng Jit Tan William S. Willis Francis S. Galasso Steven L. Suib 《Journal of the American Ceramic Society》1994,77(4):1011-1016
Amorphous boron nitride thin coatings (∼0.2 μm) have been formed on Nicalon and C-Nicaion (pre-carbon-coated Nicalon) yarns via dip coating in boric acid solution followed by heating and nitriding in NH3 gas at 1000°C. X-ray photoelectron spectroscopy (XPS) and Auger electron spec-troscopy (AES) studies have shown the formation of boron nitride. The coating was boron rich and contains oxygen. The N/B and O/B ratios range from 0.6 to 0.8 and from 0.1 to 0.25, respectively. Tensile strength measurements revealed that the BN-coated C-Nicalon yarn maintained ∼85% of its original strength while BN-coated Nicalon lost ∼85% of its original strength. Auger depth profiles showed that there was a consumption of carbon during the heating and nitridation process for both BN-coated Nicalon and C-Nicalon fibers. However, the depletion of carbon in BN-coated Nicalon fibers was much more severe than that in BN-coated C-Nicalon fibers. 相似文献